Recently researches are very active in examining the possibility of mounting a refrigerating machine such as a pulse tube (cryo) refrigerator or the like in a satellite for cooling various types of components and devices in the satellite. The pulse tube refrigerator functions by supplying pressure oscillation to a pulse tube, and as the pressure oscillation generator for generating vibration pressure, there have been proposed those using electric energy, or more specifically those each comprising a compressor driven by an electric motor and an electronically controlled switch valve provided therein. In this case, a large size solar system for converting thermal energy from the Sun to electric energy is required to be mounted on the satellite to obtain sufficient electric energy for driving the pressure oscillation generator.
In the conventional types of solar systems, however, as the conversion efficiency from thermal energy to electric energy is extremely low, it is required to use solar panels or the like with very large size for obtaining sufficient electric energy, which causes various troubles when mounted on a satellite. Therefore, there has been strong need for size reduction of a pressure oscillation generator.